Evaluation of Chilo suppressalis resistance and analysis of CRY1C expression in transgenic rice

Abstract

AbstractThe insect resistance of Bacillus thuringiensis (Bt) transgenic rice (Oryza sativa L.) is mainly determined by the transcription of the CRY1C gene and the translation process of the Cry1C protein. With this in mind, we analyzed CRY1C expression and Cry1C protein content in a transgenic Bt insect‐resistant restorer line and its F1 hybrids, evaluated the resistance to Chilo suppressalis of various lines of rice, and determined the 50% lethal concentration (LC50) of Cry1C for C. suppressalis. In four transgenic rice lines, the relative expression of CRY1C was highest at the heading stage in most tissues. Among different tissues from the same developmental stage, CRY1C expression was highest in leaves, followed by stems and panicles. The relative expression of CRY1C was higher in the parent restorer line than in the F1 hybrids. The LC50 of the Cry1C protein for C. suppressalis was 4.016 μg g−1, and the Cry1C protein expression level of transgenic insect‐resistant rice exceeded this threshold at the heading stages and in stems. We next analyzed the lethality of each strain toward C. suppressalis. After 48 h, the mortality rate of second‐instar C. suppressalis larvae feeding on transgenic stem tissue was higher at the heading stage than at the tiller stage and varied from 66.7 to 91.7%. By documenting the temporal and spatial expression of CRY1C and evaluating C. suppressalis resistance to Bt transgenic rice, the risk of pests and diseases during the rice production process can be greatly reduced.